1. Field of the Invention
The present invention relates to an antenna, and more particularly, to a digital television receiving antenna for a plug-and-play device.
2. Description of the Prior Art
There are three main technical standards in ground digital television broadcasting technology globally: ATSC (Advanced Television Systems Committee) in America, DVB-T (Digital Video Broadcasting-Terrestrial) in Europe, and ISDB-T (Terrestrial Integrated Services Digital Broadcasting) in Japan. Distinct from the traditional analog television broadcasting system utilizing NTSC (National Television Standard Committee) standard, the digital television broadcasting system transfers television signals from an analog format to a digital format. After digitized, the television signals can be further compressed using an appropriate signal processing algorithm before transmission, and thus the transmission efficiency of the operating bandwidth can be enhanced. Moreover, noises in the digitized television signals generated during the transmission can be easily removed using an appropriate signal processing algorithm, thereby greatly improving signal quality at the user end. Compared with other systems, the DVB-T system not only has the advantage of mobile reception capability, but also effectively solves the multi-path interference problems utilizing the coded orthogonal frequency division multiplexing (COFDM) standard. Accordingly, the DVB-T system is utilized in Taiwan currently.
Presently, it is common to design a digital television signal receiving or demodulating module on a small-sized system ground component in a digital television receiving device. It is also common to utilize a universal serial bus (USB) interface in a desktop or notebook computer to connect with a plug-and-play digital television receiving device. Typically, the plug-and-play digital television receiving device utilizes an external antenna, and thus an additional transmission cord for connecting the antenna to the device is necessary. The additional transmission cord not only consumes excessive space, but also degrades the portability and the appearance of the whole device. Further, frequent attachment/detachment of the transmission cord to/from the device may cause the problem of contact failure between components of the device. For example, a telescopic monopole antenna is conventionally used as the external antenna. In such a case, the whole dimension of the conventional telescopic monopole antenna in use is comparatively large, and that is an obvious drawback in practical application.